Controlling Microbial Growth Flashcards
1
Q
define sterilization
A
destruction or removal of all viable organisms
2
Q
define disinfection
A
killing, inhibition, or removal of diseases causing (pathogenic) organisms
3
Q
what are disinfectants?
A
agents, usually chemical, used for disinfection, usually used on inanimate objects
4
Q
define sanitization
A
reduction of microbial population to levels deemed safe (based on public health standards)
5
Q
define antisepsis
A
prevention of infection of living tissue by microorganisms
6
Q
what are anitseptics?
A
chemical agents that kill or inhibit growth of microorganisms when applied to tissue
7
Q
what is chemotherapy?
A
use of chemical to kill or inhibit growth of microorganisms within host tissue
8
Q
what do -cidal agents do? give examples
A
kill, bactericides, fungicides, viricides
9
Q
what do static agents do?
A
inhibit growth; include bacteriostatic and fungistatic
10
Q
when an agent is applied, do microbes die instantly?
A
nope
11
Q
how does population death occur?
A
exponentially usually
12
Q
what is a measure of an agent’s killing efficiency?
A
decimal reduction time, the time it takes the agent to kill 90% of population
13
Q
what do you need to be sure of when killing microbes? why?
A
make sure all viable but nonculturable cells are dead, because once they recover they could regain ability to reproduce and cause infection
14
Q
what are the 4 main methods of microbial control?
A
- physical
- chemical
- mechanical
- biological
15
Q
what are the 2 categories of physical agents?
A
- heat
2. radiation
16
Q
what are the 2 types of heat?
A
- dry
2 moist
17
Q
what are the 2 methods of dry heat and what is the result of each?
A
- incineration: sterilization
2. dry oven: sterilization
18
Q
what are the 2 methods of moist heat and what are the results of each?
A
- steam under pressure: sterilization
2. boiling water, hot water, pasteurization: disinfection
19
Q
what are the 2 types of radiation?
A
- ionizing
2. non-ionizing
20
Q
what is the method of ionizing radation and what is the result?
A
X-rays, cathode, gamma rays: sterilization
21
Q
what is the method of non-ionizing radiation and what is the result?
A
UV: disinfection
22
Q
what are the 2 types of chemical agents?
A
- gases
2. liquids
23
Q
what are the 2 results with gas chemical agents?
A
can either sterilize or disinfect
24
Q
what are the 2 types of liquid chemical agents?
A
- for animate objects
2. for inanimate objects
25
what are the 2 types of animate liquid chemical agents?
1. chemotherapy
| 2. antispesis
26
what are the 2 results of inanimate liquid chemical agents?
can either sterilize or disinfect
27
what are the 3 types of biological agents? what are the results of each
1. predator: antisepsis
2. virus: antisepsis
3. toxin: sterilization
28
what are the 2 methods of mechanical agents?
1. filtering liquids
| 2. filtering air
29
what is the mechanical method?
filtration
30
describe filtration (2)
1. reduced microbial population or sterilizes solutions of heat-sensitive microorganisms
2. also used to reduce microbial populations in the air
31
name and describe what is used for filtering liquids
membrane filters: porous membranes with defined pore sizes that remove microorganisms primarily by physical screening
32
list 2 methods of filtering air
1. surgical masks
| 2. HEPA filters (high-efficiency particulate air)
33
what are HEPA filters used in?
laminar flow biological safety cabinets, like in our lab
34
what does moist heat destroy? (3)
1. viruses
2. fungi
3. bacteria
35
what does boiling NOT do? (2)
1. no destroy endospores
| 2. does not sterilize
36
what does moist heat do? (mechanism) (3)
degrades nucleic acids, denatures proteins, and disrupts membranes
37
at what temperature is steam sterilization performed and what does it require?
above 100 degrees celsius and requires saturated steam under pressure
38
what is used for steam sterilization?
an autoclave
39
what is steam sterilization effective against?
all types of microbes including endospores
40
what is pasteurization?
controlled heating at temps well below boiling
41
what is pasteurization used for and why?
milk, beer, and other beverages because it kills present pathogens (but doesn't sterilize) and slows spoilage by reducing total load of present microbes with not affecting nutritional content too much
42
what is the effectiveness of dry heat sterilization compared to moist heat?
less effective, requires higher temperatures and longer times
43
describe the process of dry heat sterilization
items subjected to 16- to 170 degrees celsius for 2-3 hours
44
what is the mechanism of dry heat sterilization? (2)
oxidizes cell contituents and denatures proteins
45
what are 2 advantages of dry heat sterilization compared to moist heat?
1. does not corrode glassware and metal instrumnets as moist heat does
2. equipment less expensive than an autoclave for moist heat
46
give an example of dry heat sterilization
bench top incinerators (bunsen burners) used to flame innoculating loops in microbio labs
47
what wavelength of UV radiation is most bactiericdal and why?
260 because DNA absorbs
48
what is the mechanism of UV radiation as a control of microbial growth?
causes thymine dimers, preventing replication and transcription of DNA
49
what is UV radiation sterilization limited to and why?
limited to surface sterilization because it does not penetrate glass, dirt films, water, or other substances
50
what has UV radiation sterilization been used for?
water treatment
51
describe ionizing radiation
gamma radiation penetrates deep into objects
52
describe efficacy of ionizing radiation (what destroy and not destroy)
destroys bacterial endospores but not always effective against viruses
53
what is ionizing radiation sterilization used for?
sterilization and pasteurization of anitbiotics, hormones, sutures, plastic disposable supplies, and food
54
describe when disinfection is ideally effective
ideally effective against a wide variety of infectious agents at low concentrations and in the presence of organic matter
55
describe a drawback of antisepsis
overuse of antiseptics such as triclosan had selected for triclosan-resistant bacteria
56
list the 7 chemical agent categories
1. phenolics
2. heavy metals
3. alcohols
4. quarternary ammonium compounds
5. halogens
6. aldehydes
7. sterilizing gasses
57
what was the first widely used chemical disinfectant category?
phenolics
58
where are phenolic chemical disinfectants commonly used?
laboratories and hospitals
59
how do phenolic chemical disinfectants work? (mechanism) (2)
act by denaturing proteins and disrupting cell membranes
60
give 3 advantages of phenolic chemical disinfectants
1. tuberculocidal
2. effective in the presence of organic material
3. long lasting
61
give 2 disadvantages of phenolic chemical disinfectants
1. disagreeable odor
| 2. can cause skin irritation
62
give 2 examples of phenolic chemical disinfectants
1. pine sol
| 2. lysol
63
what category of chemical agents is among the most widely used disinfectants, antiseptics, and sanitizers?
alcohols!
64
what are the 2 most common alcohol chemical agents?
1. ethanol
| 2. isopropanol
65
describe the 3 -idals of alcohols
1. bactericidal
2. fungicidal
3. NOT sporicidal
66
what can alcohols dod in terms of viruses?
inactivate some of them
67
what is the mechanism of alcohol chemical agents? (2)
denature proteins and possible dissolve membrane lipids
68
describe the drawback of alcohol chemical agents, and what kind of situation they are better used in because of it
they evaporate pretty quickly (why they didn't cause a zone of inhibition in the lab) so they work better in a kill-on-contact kind of way
69
what are the 2 types of halogen chemical agents?
1. iodine
| 2. chlorine
70
what is iodine as a chemical agent?
a skin antiseptic
71
what is the mechanism of iodine halogens as chemical agents?
oxidize cell constituents and iodinates proteins
72
under what conditions might iodine halogen chemical agents kill endospores?
at high concentrations
73
what are 3 drawbacks to iodine halogen chemical agents?
1. skin damage
2. skin staining
3. allergies to iodine exist
74
how is iodaphor, an iodine halogen chemical agent, usually mixed for use?
iodine is complexed with an organic carrier, and is realeased slowly to minimize skin burns
75
what is the mechanism of chlorine halogen chemical agents?
oxidizes cell constituents
76
in what 3 situations are chlorine halogens used as chemical agents?
1. disinfection of water supplies and swimming pools
2. dairy and food industries
3. effective household disinfectants
77
what 3 mircoorganism types do chlorine halogen chemical agents destroy?
1. vegetative bacteria
2. fungi
3. spores
78
what does specifically chlorine GAS destroy?
sporicidal!!
79
why are chlorine halogen chemical agents not antispetics?
they can irritate skin
80
describe use of heavy metals as chemical agents (pro and con)
super effective but usually toxic
81
give examples of 5 heavy metals used as chemical agents
1. mercury ions
2. silver ions
3. arsenic ions
4. zinc ions
5. copper ions
82
what is the mechanism of heavy metals as chemical agents?
combine with and inactivate proteins, may also precipitate cell proteins
83
what are quarternary ammonium compound chemical agents? (2)
1. detergents that have broad spectrum antimicrobial activity and are effective disinfectants
2. amphipathic organic cleansing agents
84
what type of quarternary ammonium compound chemical agents are effective disinfectants? (a type of ion)
cation detergents
85
describe cationic detergents (quarternary ammonium compounds) (2)
1. kill most bacteria
| 2. stable and nontoxic
86
what do cationic detergents (quartenary ammonium compounds) NOT kill? (2)
1. M. tuberculosis
| 2. endospores
87
what 2 things inactivate cationic detergents (quarternary ammonium compounds)?
1. hard water
| 2. soap
88
describe aldehyde chemical agents in terms of reactivity
highly reactive molecules
89
what are 2 commonly used aldehyde chemical agents?
1. formaldehyde
| 2. glutaraldehyde
90
describe 2 things that aldehyde chemical agents are great for
1. sporicidal!
| 2. chemical sterilants
91
what are sterilizing gas chemical agents used for?
used to sterilize heat-sensitive materials
92
what 2 -cidal things are sterilizing gas chemical agents?
1. microbicidal
| 2. sporicidal!
93
what are the 2 methods of sterilizing gas chemical agents?
1. ethylene oxide sterilization carried out in equipment resembling an autoclave
2. vaporized hydrogen peroxide can also be used in this equipment
94
what 2 precautions need to be kept in mind when using sterilizing gas chemical agents?
1. gases are toxic
| 2. gases are also flammable
95
describe the field of using biological agents as a means of control of microorganisms
an emerging field showing great promise
96
what are the 3 natural control biological agents?
1. predation by Bdellovibrio
2. viral-mediated lysis using pathogen specific bacteriophage lysins (or bacteriophages themselves)
3. toxin-mediated killing using bacteriocins
97
describe new FDA news regarding use of bacteriophage biological control mechanisms
a spray format of using bacteriophages themselves was just approved to use on meat carcasses
98
what is the drawback of using biological control mechanisms?
they all work on only one specific microorganism each; this highly specialized nature means there is no way to make a broad spectrum form, and requires extensive culturing or testing to ensure the proper targt is chosen to actually have an impact
99
who evaluates the effectiveness of disinfectants?
EPA (environmental protection agency)
100
who evaluates the effectiveness of agens used on humans and animals?
the FDA
101
what are the 6 conditions that influence the effectiveness of antimicrobial agent activity?
1. population size
2. population composition
3. concentration or intensity of an antimicrobial agent
4. contact time
5. temperature
6. local environment
102
describe population size as an influence on the effectiveness of antimicrobial agent activity
larger populations take longer to killthan smaller populations
103
describe population composition as an influence on the effectiveness of antimicrobial agent activity
microorganisms differ markeldy in their sensitivity to antimicrobial agents
104
describe concentration or intensity of an antimicrobial agent as an influence on the effectiveness of antimicrobial agent activity (2)
1. usually higher concentrations of an agent kill more rapidly
2. but the relationship is not linear, microbes are sneaky
105
describe contact time as an influence on the effectiveness of antimicrobial agent activity
the longer the exposure, the more organisms killed
106
describe temperature as an influence on the effectiveness of antimicrobial agent activity
higher temperatures enhance chemical activity (usually making agent more effective)
107
describe local environment as an influence on the effectiveness of antimicrobial agent activity (2)
1. pH, viscosity, concentration of organic matter, and other things can profoundly impact effectiveness of an agent
2. organisms in biofilms are less susceptible to many antimicrobial agents
